Telephone-transmitter.



- PATENTBD MAY 23, 1905. l H. M. GAIL.

TELEPHONE TRANSMITTER.

APPLIOATION lEILIED JULY 7,1904.

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Z5-aveva 67 @VM UNITED STATES Patented May 23, 19o5l PATENT OFFICE;

TELEPHONE-TFzANswllTTER.`

SPECIFICATION forming part of Letters Patent No. 790,428, dated May 23, 1905.

Application led July 7, 1904. Serial No. 215,563.

To rif/ZZ whom, it may concern:

Beit known that I, HARRY M. GAIL, a citizen of the United States, residing at Buifalo, in the county of Erie and State of New York, have invented new and useful'lmprovements in Telephone-Transmitters, of which the following is a specification.

This invention relates more particularly to that class of telephone-transmitters or microphones in which a granular conductor or resistance, such as powdered carbon, is interposed between the electrodes. In transmitters of this character as heretofore constructed the carbon granules in course of time became packed, which impaired the operation of the Y transmitter. Y One of the objects of this invention is to so organize the transmitter that the carbon granules are automatically shaken during the ordinary use of the instru ment, thereby keeping the carbon loose and in the highest state of eiciency. i

Another object of this invention is to provide a transmitter which has greater power and volume, which reproduces the same waves more clearly, and in which the sound-waves are prevented from reverberating.

This invention has the further object to improve the construction of the transmitter with transmitter.

- Similar letters of reference indicate corresponding parts throughout the several views.

The housing or casing of the transmitter consists of a tubular shell or cylindrical body A, of metal, the axis of which is horizontal, and two heads or caps a a, applied to opposite ends of the body. The space within the casing is divided by metal partitions or disks B B into a central chamber, which is arranged between the partitions and two end chambers, each of which is arranged between one of the partitions and the adjacent head or cap `of the casing. The partitions and caps may be secured to the body in any suitable manner, but preferably by threading thebore of the body and screwing the partitions and caps into the body. The caps are preferably held against displacement in the body by set-screws a or otherwise.

C represents the mouthpiece of the transmitter, which is bell-shaped or flaring and has its outer large end projecting laterally from Ythe side of the body, while its small end projects transversely inward through an opening in the body into the central chamber of the same. Within the central chamber is arranged a sound-'distributer D, comprising two branch tubes or conduits d d, whereby the interior of the mouthpiece is connected with the endv nozzles the sound-distributer is'provded with annular shoulders d', which bear against the inner side of the partitions, whereby the distributer serves as a space-block for maintaining the partitions in the proper position rela` atively to each other and the distributer.

Each of the end chambers contains a complete' transmitting device, both of which are identical in construction, and the following description of one will therefore apply to both: F is a diaphragm, of aluminium or other suitable material, which is clamped at its margin between the marginal part of the adjacent partition and the corresponding cap. A washer or packing-ringf, of rubber or similar material, is preferably interposed betweenthe diaphragm and the adjacent cap for producing a uniform bearing and firmly gripping the diaphragm around its entire margin. The marginal part of the partition is raised, so that IOO ` waves, which are directed against the same by the distributer from the mouthpiece.

Gr H represent a pair of cooperating electrodes, consisting of disks of carbon or similar material, which are arranged axially within each of the end chambers and opposite each other. The inner electrode G is secured centrally to the adjacent diaphragm by a bolt g, a washer g being preferably arranged on this bolt between the diaphragm and the inner electrode. The outer electrode H is secured to the adjacent cap of the casing by a bolt I, which passes axially through a central opening in said cap, but is insulated therefrom. The head e' of this bolt bears against the inner side of the cap, but is insulated therefrom and carries the outer electrode H, while its nut t" bears against the outer side of said cap. The outer electrode may be fastened to the bolt-head e' in any suitable manner-for instance, by electroplating the back of the electrode and then soldering the same to the bolthead. Surrounding the pair of electrodes is a retaining-sleeve J, of felt or similar iibrous material, which extends from the diaphragm to the corresponding cap of the casing. A cylindrical cell is thus formed between the companion electrodes, which is iilled with a granular conductor or resistance j, such as powdered carbon or other electrical conducting substance of granular form.

The main operating parts of the transmitter thus far described are mounted in any suitable manner on a support, so that the salne may be rocked or turned in a vertical plane for adjusting the mouthpiece to the speaker. The preferred means for this purpose consists of two angular conducting-arms f: f, of metal, secured at their lower ends by screws Z Z to opposite sides of a support or standard L, constructed of insulating material. This standard may form part of a stand for supporting the transmitter on a desk in the usual manner.` The upper end of each arm is provided with a circular opening or bearing m, in which is journaled a trunnion m', which is formed concentrically on the outer end of the adjacent screw-nut Z.

One side or line, a, of the electric circuit containing the transmitter is connected with one of the conducting-arms of the support, while the other side or line, a, of said circuit is connected with the companion arm. Instead of mounting the transmitter on a standard the same may be similarly mounted on a wall or any other suitable way.

The electric current entering one of the lines passes from the same successively through the adjacent supporting and conducting arm, tru nnion,outer bolt, outer electrode,powdered carbon, inner electrode, inner bolt, diaphragm,

and partition on one side of the transmitter,

thence crosses through the body of the casing and passes successively through the partition, diaphragm, inner bolt, inner electrode, powdered carbon, outel` electrode, outer bolt, trunnion, and supporting-arm on the other side of the transmitter and out through the other line.

The sound-waves produced by speaking into the mouthpiece are directed by the branch tubes of the distributor so as to impingc perpendicularly against the diaphragms, whereby the latter owing to their resilience are caused to vibrate and alternately compress and release the carbon granules, thereby setting up pulsations or undulations in the electric current, whereby the speech is transmitted to the receiving instrument connected with this circuit in a well-known manner. rlhe fibers of the retaining-sleeves are suiiicicntly close te confine the carbon granules between the electrodes and bear firmly enough against the diaphragms so as to act as dampers for preventing false vibrations thereof.

When persons of different stature use the transmitter, they raise or lower the mouthpiece to the required position most convenient for use,whereby the transmitter is turned or rocked bodily in a vertical plane on its support. Inasmuch as the horizontal axis of the supporting-trunnion is coincident with that of the diaphragms and the cells containing the carbon granules, this rotary movement of the transmitter causes the granules to be tumbled or agitated, thereby keeping the same loose and in proper working condition. Owing to the fact that the turning of the transmitter is incidental to adjusting the mouthpiece to the speaker the carbon granules are agitated involuntarily by each speaker who shifts the transmitter, and as this occurs very frequently the granules are not permitted to become packed and impaired in operation` but are maintained in a condition of highest eiiieieney. By thus automatically shaking the granules at comparatively short intervals the transmitter is prevented from losing its original power after long and continued use and the expense of keeping the same in repair or adjustment common to other types of transmitters is avoided.

ln order to permit the transn'iitter to remain in any position to which it may be adjusted, the weight of the mouthpiece is oiiset by a counterbalanciiig-weight o. rlhe latter is preferably secured by screws 0' or otherwise on the inner side of the body diametrically opposite the mouthpiece, as shown in Fig. 3. The balancing-weightois preferably of such width that its sides are engaged by the marginal parts of the partitions when the same are screwed into the body, as shown in Fig. 2, thereby serving to properly space the partitions in addition to balancing' the transmitter.

As shown in Fig. 2, the division-wall or TOO TIO

partition p between the branch tubes of the distributer extends forwardly beyond the outlet ends of both branch tubes. By this means the sound-waves leading to each diaphragm are maintained distinct or separate and prevented from reverberating from one diaphragm to the other, thereby insuring more perfect transmission of speech.

The washer between either diaphragm and the corresponding inner electrode may be re-v placed by one of greater or lesser thickness for adjusting the distance between each.pair of electrodes and causing the same to bear properly against the granules between the same.

By attaching the electrical terminals tothe supporting-arms and conducting the current from the latter through the ytrunnions of the transmitter the use of wires in the transmitter is avoided, thereby preventing interruption in the electric current and rendering the working of the instrument absolutely reliable. If desired, the transmitting devices in one side of the casing may be omitted; but it is preferable to employ both and connect the same in series in the manner described. By this means the power of the transmitter is increased, thereby rendering, the same especially desirable for long distance service. Furthermore, by duplicating the transmitting devices the instrument is less liable to become totally disabled, because conversation can still be carried on through one of the transmitting devices if the other should become inoperative for any reason. When either side of the transmitter becomes inoperative, the same may be removed for repairs and replaced without disturbing the other side of the transmitter and without disconnecting any wires.

My improved transmitter as a whole is exceedingly simple and inexpensive in construction, reliable in operation, and has no deli cate parts which are liable to get out of order.

Although I have herein shown the preferred embodiment of my invention, it is obvious that the same may be varied without' departing from the scope of the invention.

I claim as my invention- 1. A transmitter comprising a cylindrical body having its bore threaded, caps screwed into opposite ends of the body, lpartitions screwed into the body and dividing the same into a central chamber and two end4 chambers, a mouthpiece extending transversely through the body' into the central chamber, a distributer arranged in the central chamber and having branch tubes extending from said mouthpiece through the central openings in the partitions, diaphragms arranged in the end chambers next to the partitions, a pair of electrodes arranged in each end chamber and having its members connected respectively with the adjacent diaphragm and cap, a fibrous sleeve surrounding each pair of electrodes and forming a cell betweeny the same, and a granular body arranged in each cell, substantially as set forth. l

' 2. A transmitter comprising a tubular body the axis of which is arranged horizontally, caps arranged at opposite ends of the body, diaphragms arranged vertically in the body, a mouthpiece mounted on the body and 'having branches leading to said diaphragms, bolts extending axially through the caps and having their heads arranged within the casing while their nuts are arranged outside thereof, two pairs of electrodes the inner members of which are connected with the diaphragms while the outer members are secured to said bolt-heads, a retainingsleeve surrounding each pair of electrodes and forming a cell between the same, a body of granular ,material arranged in .each cell, a trunnion formed on each of said'nuts, and a support consisting of an insulating-standard and two conducting-arms which are secured at their lower ends to said standard and are provided at their upper endswith bearing-openings in which said trunnions are journaled, substantially as set forth.

Witness my hand this 1st day of July, 1904.

HARRY M. GAIL.

Witnesses:

THEO. L. Porr, NELSON O. TIFFANY, Jr. 

